They duo have been assigned to revolve around getting the Canadian robotic arm in good shape for doing work outside ISS.

According to experts the arm is known as Canadarm2. It is one of the most crucial tools on the ISS. The arm is like an dexterous snake-like instrument that extends up to nearly 60 feet in the space and grabs large object.

The snake-like instrument was launched in 2001. The Canadarm2 has started experiencing some wear and tear. Two latching mechanisms at each end of the arm, called Latching End Effectors (LEE) have been deteriorating.

On of the LEE is typically stays attached to the ISS, anchoring the arm to the station while other is extended out into space to grab objects

Bresnik’s third spacewalk and the first for Vande Hei. The pair have been scheduled to emerge from the ISS at 8:10AM ET, and likely work on the replacement for the entire six and a half hours.

The duo astronauts will do a second space walk to lubricate the replaced LEE and replace a camera on the outside of the station. The duo astronauts will be joined by another astronaut Joe Acaba on October 10.